lib: add support for LZ4-compressed kernel

Add support for extracting LZ4-compressed kernel images, as well as
LZ4-compressed ramdisk images in the kernel boot process.

Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Yann Collet <yann.collet.73@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/decompress/unlz4.h

@@ -0,0 +1,10 @@
+#ifndef DECOMPRESS_UNLZ4_H
+#define DECOMPRESS_UNLZ4_H
+
+int unlz4(unsigned char *inbuf, int len,
+	int(*fill)(void*, unsigned int),
+	int(*flush)(void*, unsigned int),
+	unsigned char *output,
+	int *pos,
+	void(*error)(char *x));
+#endif